being from France, I came here today to share what I just found out about the optical lens module of the Denon DBP-4010UD player.
The following is true for the european version of this player, so it should be the same for the US "CI" version.
I have encountered, as many others have, a problem with the optical lens of the 4010 which didn't last very long (a few years). It wouldn't play any blu-ray disc after some time.
I had it replaced under warranty once. Then it failed again. But now the warranty coverage has expired and a repair from an authorized Denon technician is way too expensive.
So I decided to take care of it myself.
After a search of my own, I found out that the optical lens module inside the Denon DBP-4010UD looks exactly the same as the one inside the Sony Playstation 3, model name: KES-410a
On the photograph shown below, you can see the PS3 lens module on the left and the original Denon lens module on the right:
I purchased this KES-410a and placed it myself as a replacement for my old Denon optical module to see what would happen...
...And it worked just fine.
And it plays everything: CD, DVD-V, DVD-A, SACD, BD.
The KES-410a is very easy to find and very cheap too.
There are many videos available on YouTube that show how to change the lens in a PS3. I f you manage to strip down your Denon player until you can access the reading mechanism, you'll be able to replace the lens.
So if your Denon 4010 player doesn't play blu-ray discs any more, give it a try